<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .style1{
            color: red;
            font-size: 50px;
        }
        .style2{
            color: red;
            text-decoration: underline;
        }
        .style3{
            font-size: 50px;
            text-decoration: underline;
        }
        .style4{
            color: red;
            font-size: 50px;
            text-decoration: underline;
        }
    </style>
</head>
<body>
    <p class="style1">段落1</p>
    <p class="style2">段落2</p>
    <p class="style3">段落3</p>
    <p class="style4">段落4</p>
</body>
</html>